This invention relates to a video signal recording apparatus and in particular, is directed to an apparatus for recording segments of one field of video signal on a plurality of tracks, respectively.
In a conventional segment VTR wherein one field of video signal is divided into a plurality of segments and each of the segments is recorded on a plurality of tracks, there is an advantage that even if the diameter of a rotary head drum is made small, a necessary relative speed between the rotary head and a tape can be obtained. On the other hand, in the VTR of helical scanning system, a tape is wound around a rotary drum in an .OMEGA.-shape, so that a non-contact interval of the head with the tape occurs several times at each field. Apparently, a drop-out of reproducing signal will appear in the interval. In order to avoid the drop-out of the reproducing signal, it has been proposed in the prior art to employ an head for recording the video signal on the tape during the non-contact interval of the main head. This previously proposed system, however, employs a plurality of heads, so that a difference between the characteristics thereof appears on the picture screen. As a result, it is quite difficult to use the system in practice. When the interval reproduced by the auxiliary head is positioned at the center portion of the picture screen, the scattering or irregularity in the characteristics of the heads seriously affects the picture quality.
In order to prevent the signal from being dropped out with a single head, it is sufficient to record a video signal under the state that the video signal is time-compressed. In this case, however, clock signals having two different frequencies are necessary for time-compressing and/or time-expanding the video signal. As a result, not only the hardware of the apparatus becomes complicated, but also the undesired component caused by the interference between the different clock signals will be mixed into the video signal. Moreover, since the video signal is time-compressed and then recorded, the band of the video signal to be recorded is caused to be widened.
In order to prevent the signal dropout with a single head and without time-compressing the video signal, it may be considered to select a relative relation between the video signal and the rotary head in such a manner that the non-contact interval of the head is positioned in vertical blanking period of the video signal. However, in this case there is another disadvantage that a time code signal inserted into the vertical blanking period may be dropped out.